The present invention relates generally to a method for delivering abrasive particulate material under pressure, and more particularly to a method which utilizes a pressurized source to fluidize and deliver abrasive particulate material.
A conventional process, commonly referred to as sandblasting, combines abrasive particulate material, such as sand, with a pressurized source of gas, for example, air, to form an abrasive mixture under pressure and directs the abrasive mixture under pressure at a surface. Such a conventional sandblasting process is typically used for cleaning, polishing, or abrading the surface at which the abrasive mixture is directed. Existing sandblasting systems typically include a storage container adapted to contain the abrasive particulate material therein, and a pressure line through which the pressurized source of gas is directed and into which the abrasive particulate material is fed by gravity flow from the storage container.
More particularly, sandblasting has been employed to form an ink fill slot in a silicon substrate of an ink-jet printhead. Existing sandblasting systems employed for forming the ink fill slot typically rely on gravity flow, vibration of the storage container, and/or modulation of the pressure line to ensure discharge of the abrasive particulate material from the storage container, through a metering orifice, and into the pressure line. The vibration and/or modulation in these existing sandblasting systems, however, results in chaotic behavior, or inconsistent flow, of the abrasive particulate material through the metering orifice. This chaotic behavior resulting when the ink fill slot is formed with existing sandblasting systems is identified by random size and shape variations of the ink fill slot. Since the ink fill slot provides a supply of ink to a printing element of the ink-jet printhead during a printing process, a distance from the ink fill slot to the printing element effects the supply of ink to the printing element. Size and shape variations in the ink fill slot, therefore, can degrade printing performance.
Accordingly, a need exists for a system for delivering abrasive particulate material under pressure which provides consistent flow of the abrasive particulate material from a storage container, through a metering orifice, and into an output pressure line. In particular, there is a need for a method for more uniformly forming an ink fill slot in a silicon substrate of an ink-jet printhead.
One aspect of the present invention provides a method of delivering abrasive particulate material under pressure from a storage container adapted to contain the abrasive particulate material therein. The method includes communicating an inlet valve with an inlet opening of the storage container and supplying a first gas, regulated to a first predetermined pressure, to the inlet valve. The first gas is released through the inlet valve and into the storage container, and a quantity of the abrasive particulate material is discharged through an outlet opening of the storage container to an output junction. In addition, a second gas, regulated to a second predetermined pressure, is supplied to the output junction. As such, a pressurized supply of the abrasive particulate material is formed and delivered through the output junction.
In one embodiment, the third flow path is in parallel flow with the first flow path from the second flow path.
In one embodiment, the abrasive particulate material includes sand, aluminum oxide, silicon carbide, quartz, or diamond dust. In one embodiment, the gas is air and in another embodiment, the gas is an inert gas for use, for example, when a material to be processed with the pressurized delivery system is sensitive to air and oxidation of the material is a concern.
In one embodiment, the inlet valve is a one-way valve and in one embodiment, the one-way valve is a duckbill check valve which is effective at creating a tight seal when closed despite communicating with the abrasive particulate material.
In one embodiment, an adjustable control valve is provided in-line in the first flow path before the inlet valve to set a desired flow rate of pressurized gas supplied to the inlet valve. In one embodiment, a first check valve is provided in-line in the second flow path before the first flow path and the third flow path, and a second check valve is provided in-line in the third flow path. In one embodiment, a filter is provided in-line in the third flow path after the second check valve to help keep the abrasive particulate material from back streaming into the second check valve.
In one embodiment, the fourth flow path includes an inlet orifice communicating with the unoccupied portion of the interior space of the storage container to restrict input to the fourth flow path.
In one embodiment, a baffle is positioned within the storage container above the inlet opening to disperse pressurized gas released into the interior space of the storage container so as to more evenly distribute pressurized air throughout a base of the storage container. In one embodiment, a nozzle is provided at an output end of the fifth flow path for accelerating and directing the abrasive particulate material toward a surface to be processed.
Another aspect of the present invention provides a pressurized delivery system for abrasive particulate material. The pressurized delivery system includes an input pressure line having a first end adapted to communicate with a pressurized source of gas, a fluidizing pressure line having a first end communicating with the input pressure line, and a storage container adapted to contain the abrasive particulate material therein. An inlet valve communicates with a second end of the fluidizing pressure line and an inlet opening of the storage container. A back-pressure pressure line has a first end communicating with an unoccupied portion of an interior space of the storage container, and an output pressure line has a first end communicating with a second end of the input pressure line, a second end of the back-pressure pressure line, and an outlet opening of the storage container. As such, a pressurized supply of the abrasive particulate material may be formed and delivered through the output pressure line.
Another aspect of the present invention provides a method of delivering abrasive particulate material under pressure from a storage container adapted to contain the abrasive particulate material therein. The method includes the steps of communicating an inlet valve with an inlet opening of the storage container and supplying a first gas, regulated to a first predetermined pressure, to the inlet valve. The first gas is released through the inlet valve and into the storage container, and a quantity of the abrasive particulate material is discharged through an outlet opening of the storage container to an output junction. In addition, a second gas, regulated to a second predetermined pressure, is supplied to the output junction. As such, a pressurized supply of the abrasive particulate material is formed and delivered through the output junction.
Another aspect of the present invention provides a method of abrading a portion of a silicon substrate. The method includes the steps of fluidizing abrasive particulate material with a first gas within a storage container, combining the gas fluidized abrasive particulate material with a stream of a second gas to provide a stream of the gas fluidized abrasive particulate material, and directing the stream of the gas fluidized abrasive particulate material at the silicon substrate to abrade the portion of the silicon substrate.
Another aspect of the present invention provides a method of forming an ink fill slot in a silicon substrate of an ink-jet printhead. The method includes the steps of fluidizing abrasive particulate material with a first gas within a storage container, combining the gas fluidized abrasive particulate material with a stream of a second gas to provide a stream of the gas fluidized abrasive particulate material, and directing the stream of the gas fluidized abrasive particulate material at the silicon substrate to form the ink fill slot in the silicon substrate.
Another aspect of the present invention provides an ink-jet printhead including a silicon substrate having an ink fill slot formed therein by fluidizing abrasive particulate material with a first gas within a storage container, combining the gas fluidized abrasive particulate material with a stream of a second gas to provide a stream of the gas fluidized abrasive particulate material, and directing the stream of the gas fluidized abrasive particulate material at the silicon substrate to form the ink fill slot in the silicon substrate.
The present invention provides a system for delivering abrasive particulate material under pressure such that more accurately metered flow of the abrasive particulate material from a storage container, through a metering orifice, and into an output pressure line is achieved. More particularly, the present invention provides a method for more uniformly forming an ink fill slot in a silicon substrate of an ink-jet printhead.